300 Million Americans

What is the fastest growing industrialized nation (population-wise) in the world?

"The United States is the only industrialized nation with significant population growth." The US is the third most populous country, behind China and India. Apparently these countries don't count as industrialized nations. Japan and counties in Europe do, but they're not growing.

And sometime this week, the US population will reach 300 million people. This population growth is being caused not so much by Americans having babies, but primarily by Americans living longer and by people immigrating into America. (The population figures include undocumented residents and other non-citizens.) The environmental impact of so many Americans is cause for concern.